This invention relates to a water jet propulsion unit and more particularly to an improved arrangement for drawing water under pressure from such a unit.
The use of water jet propulsion units for powering watercraft is well known and widely accepted. Such units have a variety of advantages over more conventional propeller driven watercraft such as the ability to run in very shallow water. In addition, the jet propulsion unit itself may be employed as a source of external water pressure for a variety of purposes.
For example, it has been the practice to tap water off of the jet propulsion unit and pass it through a venturi type of device for pumping the bilge of the associated watercraft. Alternatively or in addition, a portion of the water pumped by the jet propulsion unit may be drawn off and circulated through the powering internal combustion engine for its cooling.
There is, however, a difficulty in the types of systems that have been previously used for drawing water off from the jet propulsion unit. Because of the ability of jet propulsion units to operate in shallow water, frequently foreign objects may be drawn into the jet propulsion unit and moved by the impeller. Such foreign objects can comprise either sea weed or even small, hard objects such as pebbles or stones. If these foreign objects are pumped into the water drawn off from the jet propulsion unit, they can clog the conduit since such conduits are normally small in size. This is particularly true when venturi type pumps are employed in that the foreign objects can easily clog the throat of the venturi. Obvious disadvantages result from such problems.
It is, therefore, a principal object of this invention to provide an improved jet propulsion unit for a watercraft or the like and which is utilized to pump additional water for an extraneous purpose.
It is a further object of this invention to provide an improved filtering arrangement for the water drawn off from a jet propulsion unit.
It is a yet further object of this invention to provide a simple filter for the external water drawn from the jet propulsion unit and one which may be easily serviced.